Fabric and method of producing same



Dec. 2l, 1954 l, s, NEss ETAL FABRIC AND METHOD oF PRODUCING SAME 5sneek-sheet 1 A TTOANE Y.

l. S. NESS ETAL.

FABRIC AND METHOD OF PRODUCING SAME Dec. 21, .1954

5 Sheets-Sheet 2 Filed April 7, 1.952

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ATTORNEY.'

Dec. 2l, 1954 l. s. Nass ErAL FABRIC AND METHOD oF PRoDucING SAME 5Sheets-Sheet 3 Filed April 7, 1952 @Mwwwwwwmwm Dec. 21, 1954 l, s.Nl-:ss ETAL Dec 21, 1954 l. s. NESS Erm.

I FABRIC AND METHOD OF PRODUCING SAME 5 Sheets-Sheet 5 Filed April 7,1952 JNVENToRs:

United States Patent FABRIC AND METHOD F PRODUCING SAME Irving S. Ness,Princeton, and Ronald V. Lints, Rahway,

l?. J., assignors to Chcopee Manufacturing Corporation, a corporation ofMassachusetts Application April 7, 1952, Serial No. 280,966

30 Claims. (Cl. 154-401) The present invention relates to textilefabrics and is more particularly concerned with so-called nonwoven"fabrics, i. e., fabrics produced from textile fibers without the use ofconventional weaving or knitting operations. The invention is of primaryimportance in connection with oriented" nonwoven fabrics composed o funspun textile fibers, the major' proportion of which are substantiallyoriented or predominantly parallelized in one difaction.

Nonwoven fabrics are conventionally manufactured at the' present time byproducing a more or less continuous web of loosely associated textileiibers disposed in sheet form (using any one of a variety of well-knownrocedures) and then bonding the sheet or web to. anc or or bond theindividual fibers together. The conventional base material for nonwovenfabrics is a web comprising any of the common textile-length fibers ormixtures thereof, the fibers varying from approximately one-half inch totwo inches in staple length. These fibers are customarily processedthrough any suitable machinery (e. g., a conventional card) to form aweb or sheet of loosely associated fibers weighing approximately from100 to 4000 grains per square yard. This essentially two-dimensional webor sheet of fibers is produced continuously with the fiberssubstantially parallelized or oriented in the machine direction, i. e.,in the direction in which the product moves continuously from thesheet-forming machine. In such a web, the degree of fiber orientationmay range from about 70% to about 90%; in other words, from about toabout 30% of the fibers will be non-oriented or randomly disposed whilethe remainder will be substantially parallelized in the machinedirection.

The bonding operation by which such a web is converted into a fabric maybe accomplished in any one of several different ways. One method is toimpregnate the web over its entire width with various well-known bondingagents such as natural or synthetic resins. Another method is to printnonwoven webs with continuous straight or wavy lines of binder extendingtransversely across the web. Still another method is to imprint on theweb a discontinuous binder pattern, consisting of discrete, physicallyseparated areas of binder, arranged in a staggered pattern.

Regardless of the bonding method used in producing a fabric from a webof oriented textile fibers, the fabrics of the prior art have beensubject to several disadvantages. Of these disadvantages, one of themost outstanding is the fact that the web is non-isotropic in respect toits physical properties; the tensile strength of the fabric transverseto the direction of fiber orientation (i. e., its cross strength), isvery much less than the tensile strength of the fabric in a directionparallel to the fiber orientation (i. e., its long strength). As aresult, prior nonwoven fabrics have been characteristically weak in thecross direction, tending to rip or tear when the web is subjected toeven a moderate extensional stress.

Generally speaking, one of the objects of the present invention is toprovide a nonwoven fabric that is not subject to the foregoingdisadvantage and which is characterized by a cross strength to longstrength ratio of approximately one-to-one. In short, one of our objectsis to produce a pseudo-isotropic non-woven fabric, i. e., one whosecross strength is substantially equal to its long strength.

Another object is the provision of a pseudo-isotropic nonwoven fabric,.a substantial lproportion of ,whose coni- 2,697,678 Patented Dec. 21,1954 ICS ponent fibers have been dimensionally stabilized or fixed in areticular structure composed of a multiplicity of sinuous or serpentinebands of fibers arranged side by side in a common plane, each band beingthe substantial mirror image or reflection of the immediately adjacentband on either side.

A further object is a pseudo cross-lay laminated fabric, i. e., theproduct having physical properties typical of one formed by cross-layingand laminating two or more plies of oriented webs, but produced inaccordance with the present invention without a true cross-layingoperation.

Still another object is to provide a nonwoven substitute for wovengauze, consisting of a gauze-like nonwoven fabric having a uniformlyopen, lacelike, reticular structure that has been dimensionallystabilized sul`n`ciently to resist deformation when stressed eithercrosswise or lengthwise of the web, the dimensional stabilization beingeffected without substantial impairment of the high porosity andabsorptive capacity of the original web from which it was produced.

Another object is an absorbent dressing provided with a nonwoven,gauze-like cover sheet.

A further object is the provision of simple commercially feasible andeconomical methods by which the foregoing product may be produced from a'non-isotropic web of substantially oriented textile fibers.

Still another object is to provide means by which the ratio of the longstrength to cross strength of an oriented web of textile fibers may bevaried within wide limits, and means by which the resulting product maybe dimensionally stabilized to a predetermined degree, also within widelimits.

Other objects and advantages of the invention will become apparent asthe description progresses in connection with the several figures of thedrawing wherein:

Fig. l is a flow sheet diagrammatically showing several processes bywhich the present invention may be carried into practice;

Fig. 2 is a graphical chart showing the change in physical properties ofone form of bonded nonwoven fabric when processed to different degreesin accordance with the present invention;

Fig. 3 is a graphical chart showing the change in physical properties ofanother type of bonded nonwoven fabric when subjected to differentdegrees of processing in accordance with the present invention;

Fig. 4 is a graphical chart showing the change in physical properties ofstill another type of bonded nonwoven fabric when subjected in differentdegrees to the process of the present invention;

Fig. 5 is a perspective view of a laminated pseudo-cross lay fabric madein accordance with the invention;

Fig. 6 is a plan view, on an enlarged scale, of a frag ment of one formof gauze-like nonwoven fabric in accordance with another aspect of thepresent invention;

Fig. 7 is a similar view of a gauze-like fabricmade from the product ofFig. 6;

Fig. 8 is a similar view of a modified form of gauzelike product inaccordance with the invention;

Fig. 9 is a similar view of a modified form of gauzelike product inaccordance with the invention;

Fig. l0 is a similar view of still another modification of thegauze-like product ofthe present invention;

Fig. 11 is a similar view of a further modification of our gauze-likeproduct;

original fabric, its binder pattern, and the type of operationssubsequently performed on the starting material depend in part on theend product to be produced. Generally speaking, however, a basicoperation used in producing therefrom all types of products in'accordance with our invention involves stretching of the prebondedfabric .in .the .cross direction while the binder is substantially inits set condition. The stretching operation involves a deformation ofthe bonded web in the plane of the fabric, increasing its dimensionstransverse to the predominant fiber direction and decreasing itsdimensions parallel to the predominant ber direction. The purpose of thestretching operation is to effect substantial reorientation of thefibers in the web, the type of reorientation accomplished depending inpart on the character of the original pre-bonded fabric and in part onthe manner in which, and degree to which, the fabric is stretched. Inany event, after the re-orientation stretching is completed, the web inits extended state is rendered dimensionally stable by re-bonding in anymanner that will satisfactorily "freeze, anchor, or fix the fibers intheir reoriented condition.

Referring now to Fig. 1, an unbonded web of oriented bers such as thatproduced by a carding operation is subjected to any type of bondingoperation to anchor the oriented fibers together. The resulting fabricwith the binder set thereon is a bonded web of oriented textile fibers.These conventional operations, well known in the art, are indicated inFig. 1 by the boxes identified as 1, 2, 3, and 4. So much was well knownbefore the present invention. Starting with such a pre-bonded web,several alternative methods of producing therefrom a pseudo isotropicweb are available in accordance with one aspect of the presentinvention. One method which is universally applicable to all pre-bondedoriented webs, is to treat the web while the binder is set but the webis wet with a rebonding agent (box 5) and then stretch the web while theweb is still wet but before the re-bonding material with which it hasbeen treated is set, after which the web is subjected to any operationto set or solidify the re-bonding binder on the fabric in its extendedstate or condition (box 7). The resulting fabric is our pseudo-isotropicfabric (box 8).

One convenient method of carrying out the process described in theimmediately preceding paragraph is to impregnate the pre-bonded web (box4) with an aqueous dispersion of binder (box 5). Then while the web isstill wet with the aqueous emulsion of binder, it is subjected uniformlyto a stretching operation which increases its width by at least 50% andpreferably 70% or more of its original width so that the width of thestretched web is about 150% to 170% of the width of the original web.The thus extended web is then subjected to a drying op eration to setthe re-bonding binder and thereby anchor the fibers in the deformed orstretched fabric to one another,

in their reoriented condition.

A variation of the method described immediately above, also applicableto any type of bonded oriented fabric, is shown in boxes 9, 10, and 11.This optional or alternate method consists in first wetting-out thepre-bonded web by any convenient procedure, for example, by submergingthe web in water (box 9). After the wet-out, the wet web is subjected toa stretching operation to increase the cross dimensions of the web by atleast 50% and preferably 70% or more (box 10). The thus stretched web istreated with rebonding agent in any convenient manner, well known in theart (box 11) and then treated (box 7) in order to set the re-bondingbinder. The resulting rebonded fabric (box 8) is also a pseudo isotropicfabric.

Still another optional or alternate route is shown in boxes 12, 13 and14. This optional route is of particular importance in the treatment oflaterally extensible island bonded webs of oriented textile fibers, i.e., webs that have been bonded together into sheet form by a binderpattern covering only a minor portion of the lateral surface of the weband comprising a multiplicity of discrete, physically separated, butnevertheless articulated areas of binder arranged in a staggeredpattern. Such webs are characterized by substantial capacity forextension in the cross direction, i. e., they may be stretched crosswiseto substantial degree without rupture of the fabric, this beingaccompanied by a major reorientation of the fibers in the web. In such aweb the individual binder areas may be any convenient form or shape,preferably one that 1s completely symmetrical, such as either adisc-shaped or a doughnut-shaped binder area.

One particularly satisfactory fabric of the above general type may beproduced by imprinting on the oriented web anarticulated, multiannulatebinder pattern covering only a minor portion of the lateral surface ofthe web. The individual areas of binder are annular or doughnut shapedand are preferably arranged in parallel courses or rows extendingtransversely across the web and also preferably in staggeredrelationship, in overlapping columns that are parallel to each other andto the direction of fiber orientation, and overlapping each other to thecxtent of about 0.02 to about 0.05 of an inch. The annular areas are sodimensioned and positioned that every imaginary line Within the overlapzone formed by the overlapping columns, and parallel to the direction offiber orientation passes through at least three discrete binder areaswithin a distance along the axis of the imaginary line equal to theaverage length of the fibers comprising the web.

As mentioned before, in order to impart to such a web substantialcapacity for lateral extension and also to preserve its textile-likeproperties, the binder pattern should cover only a minor proportion (e.g., about l0 to about 35%) of the total lateral surface of the web. Sucha binder pattern coacts with the oriented fibers of the web on thewell-known lazy tongs principle. Alternatively, but less satisfactorily,instead of employing annular binder areas, the binder areas may consistof spots or disc shaped areas arranged approximately in the same manneras the annular areas described above.

When a thus bonded web is stretched crosswise, it undergoes a lateralextension, with three highly significant results. In the first place amajor re-orientation of the originally parallelized fibers takes place,with the development of a netlike or reticular structure due to theformation of a series of parallel, sinuous, or serpentine bands offibers arranged side by side in a common plane and in apposition to eachother, each band being the reflection or image of the two adjacentsinuous bands on either side. In the second place, the collapse of thebinder pattern in one direction, which characteristically accompaniesits extension in the cross direction, tends to buckle or pucker some ofthe originally oriented fibers out of the plane of the binder patternwith the development of a uniform quilt-like pattern of tiny pillows" onthe surface of the fabric. In the third place, a substantial proportionof the nonoriented fibers in the web, when subjected to tensionalstresses as the web is extended crosswise, are either ruptured or pulledout of the binder areas. The thus released ends of the nonorientedfibers tend to bend out of the plane of the fabric proper, forming auniform nap or down on the surface of the fabric. These three factorssubstantially improve the softness of the fabric when it is stretchedcrosswise beyond its elastic limit. However, the resulting fabricbehaves as a lazy tong that has been partially extended: if the web ispulled in either direction, it tends to extend in that direction, andconcurrently collapses in the opposite direction. Accordingly the web assuch does not resist deformation in either direction: in short, it lacksdimensional stability.

Starting with an island bonded web of the above type, in accordance witha further aspect of the present invention, the fabric is stretched whileeither wet or dry. the stretching being effected in the cross direction,until major reorientation of the fibers has been effected. The thusextended web is then re-bonded in any suitable manner to anchor the webin its extended condition. One convenient way of accomplishing this isto impregnate the stretched web with an aqueous emulsion of binder, theimpregnation being carried out while the fabric is in the extendedcondition (box 14). The thus impregnated web is then dried (box 7) whilethe fabric is. in its extended condition. The thus re-bondcd webconstitutes another pseudo isotropic fabric (box 8).

The effect of varying degrees of lateral stretch before rebonding isdiagrammatically shown in Figs. 2, 3, and 4. In Fig. 2, the fabricstarting material consisted of an island bonded web treated inaccordance with the process as described in connection with Fig. 1,boxes l2, 13, 14, 7 and 8. The stretching process was interrupted atpredetermined degrees of stretch, as indicated along the vertical axis(Figs. 2, 3 and 4) by Per cent stretch before re-.bondingf After thestretch was interrupted at these percentages, the re-bonding process wascompleted via an impregnation procedure, and the properties o f thefabric finally determined. Depending upon the degree of stretchV beforethe re-bonding operation, the long tensile strength of the nished fabrictends to fall off while the cross tensile strength tends to increase. Ifthe fabric is subjected to a stretch of about before re-bonding, thenormal ratio of long-to-cross tensile strength is reversed in thefinished fabric. In other words,

if the stretching operation before rebonding involves a stretch ofgreater than 80%, the finished fabric is stronger in the cross directionthan in the long direction. Thus the long-versus-cross tensile strengthrelationship is trsed if the stretching before re-bonding exceeds aboutReferring now to Fig. 3, this shows the relationship of cross tensilestrength to long tensile strength of an overall impregnated web oforiented textile fibers treated in different degrees by the proceduredescribed in connection with Fig. 1, boxes 5, 6, 7, and 8. As indicatedin Fig. 3, at approximately stretch, before rebound ing, a reversal inthe normal cross-versus-long tensile strength is effected.

Fig. 4 shows the long tensile strength and cross tensile strength of afabric treated to dierent degrees in accordance with the presentinvention, starting with an oriented web that has been pre-bonded bycontinuous lines extending transversely across the web. Here again thereversal in the normal long-versuscross tensile `strength relationshipoccurred when the per cent stretch before the re-bonding operation wasapproximately In other words, if the continuous line-bonded web isstretched to at least 180% of its original width, and then re-bonded,the normal relationship is reversed.

The data diagrammatically presented in Figs.',2, 3, and 4 were obtainedin the following manner. The starting material consisted of an orientedweb containing 100% bright viscose, the web weighing approximately 660grains per square yard. This web was then bonded either by impregnation,island bonding, or continuous line bonding, using the same binder(polyvinyl acetate) in all cases. In the case of the line and islandbonded fabrics, the printing process followed in general the processdisclosed in Joshua Goldman Patent No. 2,039,312.

The web bonded into a fabric as described above (i. e., with the binderset) was then treated by impregnation with an aqueous polyvinyl chlorideemulsion containing approximately 35% solids. The fabrics were dipped inthe emulsion and then separately stretched to a predetermined percentageof the original width. VAfter the stretching operation, each impregnatedweb, while still wet, and still in its extended condition, was placed ona hot plate to dry the web and set the binder. weight of the finishedfabric was approximately 760 grains per square yard.

The pseudo-isotropic fabric prepared by any of the methods describedabove may be used in the production of a pseudo-cross lay laminatedfabric. Referring to Fig. 1, boxes 15, 16, 17 and 18, the pseudo-crosslay process consists essentially in plying the pseudo-isotropic web (orone of its precursors products immediately following the stretchingoperation) either with an unbonded web of oriented fibers (box l) or anyother fabric, such as the bonded starting material (box 4). Thelaminated product may consist of two or more plies, involving one ormore plies of the "pseudo-isotropic web or its precursors. The laminatedfabric is then bonded together in any suitable manner and the binder isset so that a laminated fabric is formed.

A typical pseudo-cross lay fabric, as shown in Fig. 5 may consist, forexample, of an unbonded web 10 as one ply, and a pseudo-isotropic web 12as the other ply. The pseudo-cross lay product can be obtained, ifdesired, in a continuous manner in the following fashion: The unbondedweb (Fig. 1, box 1) is continuously subjected to the operations 2, 3, 4,5, 6, 7, and 8. The resulting pseudo-isotropic web is then continuouslyplied with an unbonded web of oriented fibers constituting the startingmaterial (box 1). The plying operation may be effected quite simply bycontinuously passing the plied webs between hot calender rolls heated toa temperature sufficient to soften the binder employed in making thecornponent lamina.

As an example of the pseudo cross-lay product described above, a web oforiented textile fibers weighing approximately 660 grains per squareyard was imprinted with the multiannular binder pattern. The bonded webwas a fabric Weighing approximately 750 grains per square yard. Thisfabric was dipped in the impregnating emulsion described above, theexcess was then squeezed out, and the fabric was stretched 137% of itsoriginal width. The thus stretched fabric was dried in the extendedcondition and then plied with another portion The of the originalmultiannular bonded material' before it had been subjected to thestretching and impregnatng operation. The plying operation wasaccomplished merely by passing the plies through hot calender rolls,steam heated to 250 to 300 F. The resulting two-ply fabric had a weightof 2560 grains per square yard; a long tensile strength of 24 pounds perinch width; and a cross tensile strength approximately the same.

Another aspect of our invention involves vthe production of a gauzelikeproduct by a modification of the procedures described above. Thestarting material for a preferred type of gauzelike product consists ofa lightweight annulate-bonded web weighing about to 200 grains persquare yard. When such lightweight fabric is stretched crosswise to asubstantial degree, there is formed a uniformly open, lacelike,reticular product, which is highly porous and adsorptive. As a gauzesubstitute it is subject to the disadvantage that it is extensible ineither direction, behaving in effect like a fishing net, on the lazytongs principle. In other words, if the fabric is pulled in a directionthat is either parallel or perpendicular to the axes of its sinuousbands, the fabric deforms. This dimensional instability of the productin either direction limits its usefulness as a gauze substitute.

In accordance with another aspect of our invention the dimensionalinstability of such a web may be overcome without substantiallyirnpairing its absorptive properties. One method of accomplishing thisis to employ a rebonding binder pattern that covers only a minorproportion of the lateral surface of the web, but which is relativelyinextensible in a direction either transverse to or parallel with theaxes of the sinuous bands. One way of giving dimensional stability tosuch a web is to use either continuous or broken line bonding in therebonding operation as shown, for example, in Figs. 6 to ll, inclusive.

In Fig. 6, the rebonding operation involves over-print ing on theextended fabric a gridlike binder pattern con sisting of two series ofparallel, continuous and preferably fine lines of binder, one seriesbeing transverse to and the other series being parallel with, thesinuous bands comprising the web. The resulting fabric consists of amultiplicity of sinuous bands of fiber 20 and 22 arranged in opposedpairs that are the substantial reflection or mirror image of each other.The binder areas 24 originally holding said bands into a self-sustainingweb are supplemented by a gridlike pattern formed by two series ofparallel, continuous, fine lines of binder 26 and 28. One of theseseries of parallel lines 26 extends continuously across the fabric,transversely with respect to the axes of said sinuous bands. The otherseries 28 of continuous fine lines of binder extends in the directionperpendicular to that of the first mentioned series 26. The bindingareas 24 of the original fabric preferably but not necessarily lie inthe centers of the overlying grid pattern formed by the intersection ofthese two series of lines 26 and 28. The resulting fabric has auniformly varying fiber density which is highest at the locus of thesinuous bands 20 and lowest at the center of each square of the grid.This low density central portion lying in the centers of the gridpattern renders the resulting fabric pervious or porous and gives it itsuniformly open, lacelike, reticular structure. The grid overbinderpattern imparts dimensional stability to the web without substantiallyimpairing its absorptivecapacity.

The binder material from which the original and second or rebondingbinder patterns are prepared need not necessarily be identical. As amatter of fact, it is sometimes preferable to use different binders inthe rst andv second bonding operations. For example, the original binderused for discontinuously bonding the original oriented web may consistof a water-soluble binder such as starch, polyvinyl alcohol,carboxymethylcellulose, or any well-known equivalent material. Thesecond binder may consist of any of the Water insoluble binder-mediawell known in the art, e. g., polyvinyl acetate, polyvinyl chloride,rubber latex or the like. In this case, after the second or rebondingoperation, the original watersoluble binder areas (24, Fig. 6) may beremoved from the fabric by immersing it in water long enough to dissolvethe original binder. Such an expedient further improves the porosity andabsorptive capacity of the resulting;

fabric, rendering it still more satisfactory for certain ap-lplications. The resultant fabric, diagrammatically -shown in Fig. 7, issubstantially identical with that shown 1n Fig.A

6, except that the original binder areas (24, Fig. 6) have been removed.

An alternative rebonding binder pattern is shown diagrammatically inFig. 8. In this instance, dimensional stability is imparted to the basicweb by two seriesfof zig-zag lines of binder, generally indicated by 30,both series extending obliquely across the fiber direction, but inopposite senses or direction. The segments comprising each zig-zag linein the series are long enough to interconnect corresponding points (34and 36) on the opposed pairs of sinuous bands and corresponding points(34 and 38) on the ascending and descending sides ot the nodes in eachsinuous band. The resulting fabric has good dimensional stability, but acertain amount of give or elasticity in the cross and long directions.

Another alternative which also imparts a slight amount of give orelasticity in the cross and long direction is shown diagrammatically inFig. 9. In this instance, the overprinted grid comprises a lattice-likeor diamondshaped pattern formed by two series of parallel, straight,fine lines of binder (42 and 44), each series being inclined withrespect to the axes of the sinuous bands but in opposite senses ordirections.

Still another means of imparting dimensional stability, but a slightamount of give or elasticity to the web is shown in Fig. 10. In thiscase, the overprinted, stabilizing binder lines 46 and 48 form doublediamonds extending generally across the two axes of each of theparallelograms formed by opposed sinuous bands of fibers. Thus the lazytong action of the original fabric is restrained by the lazy tongfaction of the stabilizing binder, acting in a reverse sense with respectto the action of the first lazy tong. As one lazy tong opens, the othercollapses, and vice versa.

Still another stabilizing arrangement which imparts a degree ofspringlike recovery action to the base fabric is diagrammatically shownin Fig. 1l. In this instance, the stabilizing binder pattern is formedby two series of parallel, broken lines of binder generally indicated as50 and S2, extending obliquely across the web at approximately the sameangle, but in the opposite senses or directions. The elongated areas orsegments of one series 50 lie in the interscgmental spaces of the otherseries 52. Each segment is long enough to interconnect opposite sides ofthe parallelogram formed by two opposed nodes of the pair of sinuousbands and 22.

One application of the fabric produced as described in connection withFigs. 6 to ll is in the production of absorbent dressings. Figs. l2 and13 illustrate this type application in connection with a catamenialdevice of the sanitary napkinf type. any suitable absorbent core 60 issurrounded by a cover 62 folded about the core and usually overlapped asindicated at 64. The core may be made of any known and suitablematerial, such as cotton fibers, paper, fiuffed' The sheet material usedfor` paper pulp, and the like. the cover comprises any of the fabricsdescribed above in connection with Figs. 6 to ll, preferably when madefrom lightweight oriented webs weighing from 100 to 200 grains persquare yard. For illustrative purpose, we have diagrammatically shown anapkin covered with the product described in connection with Fig. 9. Jnsuch an application of our fabric, the overgrid stabilized binderpattern gives the cover a desirable degree of dimentional stability whenthe tabs 66 are under tensional stress in use.

In carrying the present invention into practice, any of the conventionalweb-forming, printing and drying operations, well known in the art, andany of the conventional binder media of the prior art may be used.Typical procedures and binder media applicable in the practice of thepresent invention include those disclosed in.

the Joshua Goldman Patent 2,039,312 or the Joseph G'oldman Patent2,407,548 or the Esther Goldman Patent 2,545,952. These operations andmedia, being well known and conventional, need not be described herein,since reference may readily be made to the prior art, including thepatents mentioned.

Having now described the invention in specific detail and exemplifiedthe manner in which it may be carried into practice, it will be readilyapparent to those skilled in the art: that innumerable variations,arnplifications, modifications, and extensions of the basic principlesinvolvedV may be made without departing from its spirit or scope.- Forexample, although we have illustrated one appli-1 Referring to Figs. l2and l3,

cation ofthe invention in the'preparation of a sanitary napkin, it willbe apparent that various types of fabric produced as herein describedmay be made from webs ranging from lightweight webs (e. g., to 500grains per square yard) all the way to heavy weight webs (e. g., 500 to5000 grains per square yard). The resulting fabrics may be used in themanufacture of various types of surgical, medical, and first'aiddressings and related supplies from the lightweight, gauzelike fabricsin accordance with our invention or in the manufacture of industrialfabrics, such as artificial leather, from the heavier fabrics. Asanother example of a modification, the first or the second bondingoperations, or both, may be carried out by hot printing a thermoplasticbinder, as shown in the Esther Goldman Patent 2,545,952; or either orboth bonding operations may be effected by wet printing as shown in theJoshua Goldman Patent 2,039,312. In some instances it may be preferablefirst to hot print, cool to set the binder, then stretch, and finallyre-bond by the Wet print technique. This modification eliminates theneed for twice evaporating water from the web, as would be necessary ifwet-printing were employed in the first bonding operations andstretching were thereafter carried out with the web in the wetcondition. These and manyother modifications will be readily apparent tothose skilled in the art. We therefore intend to be limited only inaccordance with the appended patent claims.

The term textile fibers as used herein includes the conventional textilefibers whichl are capable of being spun into yarn and woven into cloth.Generally speaking this includes fibers whose average length is aboutone-half inch or longer.

We claim:

l. A method which comprises stretching an oriented web of textile fibersunited into a self-sustaining sheet by a binder infused into. the web,the stretching being carried out while the binder is set and in adirection normal to the direction of orientation of said fibers; andthen rebonding the web in its extended state.

2. A method of treating anonwoven fabric prepared by bonding a web offibers predominantly aligned in one direction, which comprises deformingthe pre-bonded fabric in the plane of the fabric by increasing itsdimensions transverse to the predominant fiber direction and decreasingits dimensions parallel to the predominant ber direction, the deformingoperation being carriedl out while the binder is set; and thenadhesively anchoring the fibers in the deformed fabric to one another.

3. A method of treating a nonwoven fabric prepared by bonding a web offibers predominantly aligned in one direction, which comprises deformingthe pre-bonded fabric in the plane of the fabric by increasing itsdimensions transverse to the predominant fiber direction and decreasingits dimensions parallel to the predominant fiber direction, the fabricdensity in weight per square unit of area remaining substantiallyconstant; applying a potential rebonding composition to the deformedfabric; and developing the bonding properties of the rebondingcomposition to anchor the fibers of said fabric to one another.

4. A method which includes providing a web comprising a major proportionof oriented textile fibers and a minor proportion of non-orientedtextile fibers, said fibers being united into a self-sustaining sheet bya binder infused into at least a portion of the lateral surface of saidweb; stretching said web in a direction transverse to the direction offiber orientation, While the binder is set but the web is wet, wherebyto effect reorientation of said fibers; applying tothe stretched webWhile in its extended state a rebonding binder; and setting therebonding binder while the web is in its extended state, to fix the`.veb in predominant fiber direction, the fabric density in Weightl persquare unit of area remaining substantially constant; and developlng thebonding properties of the rebonding composition to anchor the fibers ofsaid fabric to one another.

6. A method which includes providing a web comprising a major proportionof oriented textile fibers and a minor proportion f non-oriented textilefibers, united into a self-sustaining sheet by a binder infused into atleast a portion of the lateral surface of said web; stretching the webin a direction transverse to the direction of fiber orientation, whilethe binder is set but the web is wet, whereby to effect reorientation ofthe originally oriented fibers; applying to the web while in itsextended state a rebonding binder; and setting the rebonding binderwhile the web is in its extended state, to fix the fibers in theirreoriented state.

7. A method of making a pseudo isotropic fabric from a web comprising amajor proportion of oriented textile fibers and a minor proportion ofnon-oriented textile fibers united into a self-sustaining sheet by abinder infused into at least a portion of the lateral surface of saidweb and set therein: which method comprises stretching said web in adirection transverse to the direction of fiber orientation, while theweb is wet, to effect reorientation of said fibers; applying to the weba rebonding binder; and setting the rebonding binder while the web is inits extended state, to fix the fibers in their reoriented state andproduce a fabric that is substantially isotropic in its physicalproperties.

8. The method of claim 6 wherein said web is stretched to at least 150%of its original Width.

9. The method of claim wherein said web is stretched to at least 170% ofits original width.

10. A method of making a pseudo isotropic fabric from a web comprising amajor proportion of oriented textile fibers and a minor proportion ofnon-oriented textile fibers, united into a self-sustaining sheet by abinder infused into at least a portion of the lateral surface of saidweb and set therein; which method comprises impregnating said web withan aqueous emulsion of binder; stretching the impregnated web in adirection transverse to the direction of fiber orientation while the webis wet; and then setting said impregnating binder to fix the web in itsstretched condition.

1l. A method of treating a nonwoven fabric prepared by bonding a web offibers predominantly aligned in one direction, which comprises applyingan aqueous liquid to the fabric; applying a potential bondingcomposition to the fabric; deforming the fabric in the plane of thefabric by increasing its dimensions transverse to the predominant fiberdirection and decreasing its dimensions parallel to the predominantfiber direction, the fabric density in weight per square unit of arearemaining substantially constant; developing the bonding properties ofthe applied bonding composition to anchor the fibers of said fabric toone another and removing the liquid from the fabric.

12. In the manufacture of pseudo isotropic fabric from a web comprisinga major proportion of oriented textile bers and a minor proportion ofnon-oriented textile fibers, united into a self-sustaining sheet by abinder infused into at least a portion of the lateral surface of saidweb; the improvement which comprises impregnating said web with anaqueous dispersion of binder; stretching the impregnated web across thedirection of fiber orientation, beyond the elastic limit of said web,while the web is still wet with said aqueous dispersion of binder; andthen drying the web in its extended state, to set the impregnatingbinder and fix said web in its extended state.

13. In the manufacture of a pseudo isotropic fabric from a bonded webcomprising a major proportion of oriented textile fibers and a minorproportion of nonoriented textile fibers united into a self-sustainingsheet by a binder infused into at least a portion of the lateral surfaceof said web, the improvement which comprises: stretching said web acrossthe direction of fiber orientation beyond the elastic limit of said web,while the web is wet with water; applying to the web a rebonding binder;plying said stretched web with another web; and then drying theresultant laminated structure.

14. The method of claim 13 wherein said web is stretched to at least170% of its original width.

15. A pseudo isotropic web comprising a multiplicity of generally snuousfiber bands disposed side by side in a common plane in opposition toeach other; each of said bands comprising a multiplicity of textilefibers substantially oriented with the axes of the band in which theyare disposed; said bands being held in spaced relationship to each otherby a binder anchoring the bers of said web together.

16. A pseudo isotropic web comprising a multiplicity of generally snuousfiber bands disposed side by side in a common plane in opposition toeach other; each of said bands comprising a multiplicity of textilefibers substantially oriented with the axis of the band in which theyare disposed; said bands being held together in spaced relationship by abinder infused into the body of said web over substantially the entirelateral surface thereof.

17. A pseudo isotropic web comprising two series of uniformly spaced,substantially symmetrical, snuous bands of bers arranged in opposedadjacent pairs that are approximately the reflection of each other; athird series of bands of fibers one member of which series is interposedbetween each of said opposed pairs of snuous bands of the first twoseries, each of said bands of the three series comprising a multiplicityof unspun textile fibers substantially oriented with the axis of theband in which they are disposed; said bands being held together in aselfsustaining web in spaced relationship to each other by a binderinfused into the body of said web and covering a substantial proportionof the entire lateral surface thereof.

18. A nonwoven, pseudo isotropic web comprising two series of uniformlyspaced, substantially symmetrical, snuous bauds of fibers arranged inopposed adjacent pairs that are approximately the reection of eachother; a third series of bands of fibers one member of which series isinterposed between each of said opposed pairs ot sinuous bands andcontiguous thereto at their points ofapposition; each of said bands ofthe three series comprising a multiplicity of unspun textile fiberssubstantially oriented with the axis of the band in which they aredlsposed; said bands being bonded together intov a selfsustaining web,and in spaced relationship to each other, by discrete areas of binderinfused locally into said series of bands and bonding one member ofeachof said series of bands at their points of apposition; said bandsbeing additionally held together in spaced relationship to each other bya binder infused into the body of said web,

over substantially the entire lateral surface thereof.

Y 19. A laminated' fabric comprising a plurality of plies bondedtogether, at least one of said plies comprising a pseudo isotropic web,comprising a multiplicity of generally snuous fiber bands disposed sideby side in a corn-4 mon plane in opposition to each other, each of saidbands comprising a multiplicity of textile fibers substantially orientedwith the axis of the band in which they are disposed; said bands beingheld together in spaced relationship to each other by a binder infusedinto the body of said web and covering substantially the entire lateralsurface thereof.

20. A nonwoven fabric having a substantially open, lacelike, reticularstructure, comprising a multiplicity of substantially snuous bandsdisposed side by side in a common plane and in opposition to each other,each band being the substantial refiection of the two adjacent bands oneither side, each of said bands comprising a multiplicity of textilefibers substantially oriented with the snuous bands in which they aredisposed; the bands being bonded together into a self-sustaining web bya binder pattern comprising lines of binder interconnecting eitheradjacent or opposed sides of the figures defined by any two opposednodes of each pair of said snuous bands.

21. A nonwoven fabric having a substantially uniformly open, lacelike,reticular structure, comprising a multiplicity of substantially snuousbands disposed in the common plane side by side in opposition to eachother, each band being substantial reflection of the two-adjacent bandson either side, with the axes parallel and their point of apposition injuxta-position, each of said bands comprising a multiplicity of unspuntextile fibers substantially oriented with the snuous band in which theyare disposed; the bands being bonded together into a self-sustaining webby two binder patterns, one pattern comprising discrete binder areasinfused locally into the fibers of each pair of adjacent bands at theirjuxtaposed points of apposition, the other pattern comprising two seriesof substantially parallel, uniformly spaced lines of binder, one seriesextending transversely across, and the other parallel to, the axes ofsaid snuous bands.

22. The product of claim 21 wherein the discrete areas of said firstbinder pattern lie in between the lines of said second binder pattern.

2.3- Ihe product of claim 21 wherein the areas of Said first binderpattern are disposed substantially in .the Center of the. grid formed.by the. .Second binder pattern 24. The product of claim 21 wherein saidlines. of binder comprise continuous or uninterrupted lines of binder.

25. A method of making a nonwoven fabric which comprisescross-stretching Ya discontinuously bonded, laterally extensiblelightweight web of substantially orient/ed textile fibers until theoriginally oriented fibers are reoriented into substantially sinuousbands disposed along parallel axes, each band being in apposition to itstwo neighboring bands; and then stabilizing said webs by rebonding theweb with a binder pattern comprising two series of uniformly spacedlines of binder, one series intersecting the other series, whereby toprovide a nonwoven fabric having a uniformly open, lacelile, reticularstructure and characterized by its resistance to deformation whenstressed either crosswise or lengthwise of the web.

26. A method of making a nonwoven fabric which comprises uniformlycross-'extending a discontinuously bonded, laterally extensible,lightweight web of substantially oriented textile fibers, until theoriented fibers are reoriented to form substantially sinuous bandsdisposed along parallel axes, each band being in opposition to its twoneighboring bands; and then imprinting o n the stretched web a gridlikebinder pattern comprising two series of substantially parallel lines,one series extending transversely across, and the other parallel to, theaxes of said sinuous bands, the lines forming said gridlike patternlying in the spaces between said discrete binder areas in the originalweb from which the product was produced.

27. A method of producing a nonwoven fabric which comprises bonding .asubstantially oriented web of textile fibers with a'discontinuous binderpattern covering a minor proportion of the lateral surface of the weband comprising a multiplicity of uniformly spaced, discrete areas ofbinder, physically separated from, vbut articulated with, each otherl byunbonded lengths f fibers; uniformly stretching the thus `bonded web ina direction transverse to the direction .of fiber orientation, ,untilthe originally oriented fibers are reoriented into substantially sinuousbands disposed along parallel axes; and then rebonding said web with agridlike. pattern comprising 4 two series of substantialy parallellines, one series ex.

tending transversely across, and the other series Parallel to, the axesof seid sinuous bends, whereby to provisie. a nonwoven fabric having euniformly open, laoeiike, ref ticular structure and characterized by itsresistance to deformation when stressed either cross'wise or lengthwiseof the web.

28. A nonwoven fabric having a uniformly IaceJike, reticular structure,said lfabric comprising a multiplicity of substantially sinuous bandsdisposed in a common plane side by side in apposition to each other,each band being the substantial reflection or mirror image of the twoadjacent bands on either side, with their axes parallel and their pointsof apposition in juxtaposition, each of said bands comprising amultiplicity o f unspun textile fibers substantially oriented with thesinuous bands in which they are disposed, the bands being bondedtogether into a self-sustaining web by two binder patterns, one patterncomprising discrete binder areas infused locally into the bers of eachpair of adjacent bands at the juxtaposed points of apposition, the otherpattern com-V prising two series of substantially parallel, uniformlyspaced lines of binder, one series of lines intersecting the otherseries of lines.

29. The fabric of claim 28 wherein said lines of binder compriseinterrupted or broken lines.

30. The fabric of claim 28 wherein said lines of binder comprisecontinuous or uninterrupted lines.

References Cited in the tile of this patent i UNITED STATES PATENTSNumber Name Date 1,507,949 Augier Sept. 9, y1924 1,831,403 Woodward Nov.l0, 193l 2,039,312 Goldman May 5, 1936 2,055,410 Hurst et al. Sept. 22,1936 2,407,548 Goldman Sept. l0, 1946 2,498,197 Baxter Feb. 2l, 19502,503,024 Boese et al. Apr. 4, 1,950 2,545,052 Goldman Mar. 20, 19512,550,686 Goldman M ay l, 1,951

FOREIGN PATENTS Number Country Date 549,254 Great Britain Nov. l2, 194,2

500,020 Belgium Dec. 30, 1950

25. A METHOD OF MAKING A NONWOVEN FABRIC WHICH COMPRISESCROSS-STRETCHING A DISCONTINUOUSLY BONDED, LATERALLY EXTENSIBLELIGHTWEIGHT WEB OF SUBSTANTIALLY ORIENTED TEXTILE FIBERS UNTIL THEORIGINALLY ORIENTED FIBERS ARE REORIENTED INTO SUBSTANTIALLY SINUOUSBANDS DISPOSED ALONG PARALLEL AXES, EACH BAND BEING IN OPPOSITION TO ITSTWO NEIGHBORING BANDS; AND THEN STABILIZING SAID WEBS BY REBONDING THEWEB WITH A BINDER PATTERN COMPRISING TWO SERIES OF UNIFORMLY SPACEDLINES OF BINDER, ONE SERIES INTERSECTING THE OTHER SERIES, WHEREBY TOPROVIDE A NONWOVEN FABRIC HAVING A UNIFORMLY OPEN, LACELIKE, RETICULARSTRUCTURE AND CHARACTERIZED BY ITS RESISTANCE TO DEFORMATION WHENSTRESSED EITHER CROSSWISE OR LENGTHWISE OF THE WEB.